With development of communications technologies, various types of user terminals emerge. Wearable devices are widely applied because the wearable devices have a small size and are convenient to carry, for example, products such as a watch and a wrist strap supported by a wrist, shoes and socks supported by feet or other products worn on legs, glasses, a helmet, a headband, and the like supported by a head, and products in various forms such as smart clothes, smart school bags, smart canes, and smart accessories.
Wearable devices are becoming multifunctional and portable. Therefore, most wearable devices can support application software and a mobile communication function. For example, some wearable devices support a subscriber identity module (SIM) card.
However, most wearable devices have a relatively small size, and can carry a battery of a limited size. Therefore, a wearable device usually has a relatively short battery standby time. However, application software and a communication function both need support of a relatively large quantity of electricity. As a result, if these functions are started, power consumption is increased. Consequently, the battery standby time of the wearable device is shorter, and practicality is reduced.